1. Field of the Invention
The present invention relates to supported catalysts, more specifically to supported catalysts containing nanometer sized platinum particles dispersed throughout the catalyst support material.
2. Description of the Related Art
Many industrial products such as fuels, lubricants, polymers, fibers, drugs, and other chemicals would not be manufacturable without the use of catalysts. Catalysts are also essential for the reduction of pollutants, particularly air pollutants created during the production of energy and by automobiles. The majority of industrial catalysts are composed of a high surface area support material upon which chemically active metal nanoparticles (i.e., nanometer sized metal particles) are dispersed. The support materials are generally inert, ceramic type materials having surface areas on the order of hundreds of square meters/gram. This high specific surface area usually requires a complex internal pore system. The metal nanoparticles are deposited on the support and dispersed throughout this internal pore system, and are generally between 1 and 100 nanometers in size.
The effect of nanoparticle size on catalytic activity is recognized in the current art. An article by Alexis T. Bell entitled, “The Impact of Nanoscience on Heterogeneous Catalysis,” Vol. 299, Science, Mar. 14, 2003, teaches that the reactivity and selectivity of catalyst nanoparticles are strongly dependent on their size. FIG. 1 is a diagram from this article which shows that the catalytic activity (in particular, CO oxidation) of Au particles is sensitive to their size and that only particles in the range of 2 to 3 nm are active.